Almost half of children 11 years old and younger suffer from dental caries, making caries one of the most common chronic diseases of childhood. Low income and minority children bear a disproportionate portion of this burden. In Chicago, these disparities are obvious with 63% of Chicago-area 3rd-graders having dental caries and over half of these caries are untreated. Pediatric dental caries are associated with pain, more severe infections, malnutrition, speech difficulties, poor school performance, cosmetic problems, and an overall lower quality of life. While many oral health interventions have been developed to reduce the incidence of caries, even the most successful programs have limited effectiveness in high risk children. The delivery and receipt of proper preventive oral healthcare involves social and environmental factors that operate on individual, family, and community levels. Multi-level interventions recognize the need to target these levels simultaneously but multi-level oral health interventions for the primary prevention of dental caries are lacking. COordinated Oral health Promotion (CO-OP) Chicago brings together a team of clinical pediatricians and dentists, researchers, health psychologists, and policy experts to rigorously test the ability of an oral health promotion intervention to improve child and family oral health. The primary intervention is family-focused education and support from community health workers (CHWs); this intervention will be applied in a range of settings to determine which settings, or combination of settings, result in the best outcomes. The Aim of the UH2 Phase is to formalize partnerships and finalize study design and protocol. This includes: 1) A formative assessment to determine partner operations, resources, and needs; 2) CHW training; 3) Pilot testing of recruitment and intervention protocols; 4) Creation of a final Manual of Procedures; and 5) Obtain clearances/contracts from all institutional and community partners. The UH3 Phase then implements and evaluates the intervention in 15 clinics, 15 WIC sites, and 1520 individual families. Aim 1 is to evaluate the ability of a clinic-based family-focused CHW intervention to improve child oral health; Aim 2 evaluates the ability of a WIC-based family-focused CHW intervention to improve child oral health; Aim 3 evaluates the ability of a home-based family-focused CHW intervention to improve child oral health; and Aim 4 determines the added value of combining interventions. The hypothesis is that participants receiving home-based CHWs and clinic-based or WIC-based CHW interventions will have the best oral health outcomes at 12-months. The primary outcome is incidence of early childhood caries, determined by the Caries Severity Index. The study will also employ the RE-AIM framework (Reach, Efficacy, Adoption, Implementation, Maintenance) to evaluate program effectiveness. The results of this study have the potential to influence oral health programming, workforce development, and reimbursement on the local, state, and national level.